The present invention relates to methods and apparatus for displaying information and, more particularly, to methods and apparatus for efficiently displaying and updating information, e.g., device-status information, at a location which is remote from the source of the information.
From a device or system management standpoint, it is often useful to know the status of one or more devices at any given time. In order to facilitate device and/or system management, monitoring devices are frequently used to collect device-status information. The collected information is then processed and, in many cases, transmitted to a physically remote management system for display to a human operator.
Displayed images that indicate the status of one or more corresponding physical or logical devices are sometimes referred to as device mimics. Device mimics may be implemented as a graphical representation of one or more devices and the status of the device(s). For example, a device mimic may be used to represent a network router and to display the status of various ports included in the network router.
The growing use of networked computers, i.e., intranets, and the growth of the now well known global Internet, provide a convenient infrastructure that can be used to transmit device-status information. Frequently, device-status information is transmitted using an intranet or the Internet to a management system so that it can be displayed to a human system administrator or other individual overseeing device and/or system operation.
Web browsers, such as Microsoft Corporation""s Internet Explorer, offer a convenient way to access and display information via an intranet or the Internet. Web-browser-based management systems can be intuitive and easy to use. This makes them well suited for use by novice and non-expert users.
A typical Web browser enables a user to view, or xe2x80x9cbrowsexe2x80x9d, documents located on the World Wide Web, another network, or a user""s computer. Documents on the World Wide Web, called pages or Web pages, are normally written in HTML (hypertext markup language). A typical Web page comprises one or more HTML documents that enable a user to follow hyperlinks, transfer files, display graphics, play audio and video files, and execute small programs, such as Java applets, embedded in the HTML documents. Thus, Web browsers are commonly used to display images, including mimics, transmitted as part of a Web page.
As is known in the art, HTML documents contained in a Web page that represent a display are referred to as frames. Each frame generally comprises a rectangular section of a Web page that is a separate HTML document. Web pages usually have multiple frames, each of which is a separate HTML document. Each HTML document or frame typically contains HTML files that comprise image descriptions, image positioning information and instructions, e.g., routines for performing various operations. JavaScript routines may be included in these HTML files to perform various operations, including updating the visible contents of a frame that is displayed as part of a screen in which other frames are also displayed.
In browser-based management systems, mimics are sometimes implemented as HTML documents that include a full description of the device mimic to be displayed. Activation of a hypertext link is one method used to initiate downloading, e.g., updating, of displayed HTML documents.
In one known network management tool, a Web browser and a device mimic are used to display network device port status information to a user of a management system. In such a system, the device mimic is generated as part of a set of HTML documents that fully describe the device mimic. In addition to the device mimic, control information, e.g., optional commands, may be displayed. The device mimic is usually composed of a number of separate sub-images, some of which never change while others may change as a result of device-status update information.
In the known system discussed above, HTML documents representing a device mimic are regenerated each time the status information is to be updated, e.g., in response to manual activation of a refresh hyperlink. The updated HTML documents containing the description of the entire mimic is then transferred as a Web page from the monitoring device to the management system where the mimic is to be displayed.
Regenerating a new Web page with all of the necessary HTML documents needed to describe an entire mimic can entail significant device and network resources. The size of an HTML document representing an entire mimic may be significant, e.g., 30K bytes in some applications. It may take a monitoring device considerable time, e.g., 15 seconds of device processing time in some cases, to regenerate the HTML description of the entire mimic. The time needed to generate the HTML documents is in addition to the amount of time and network resources required to transmit the Web page containing the mimic from the monitoring device to the management system. These overheads are incurred regardless of the amount, if any, of a device""s changes in status.
Thus, to conserve network, monitoring device, and/or management system resources, mimic updating techniques of the type described above tend to find limited application in known monitoring systems. For example, device-status updates may be limited to points in time when a human operator of the management system that displays the mimic manually initiates a screen refresh by activating a refresh hyperlink, for example, by double clicking on a displayed text or an icon representing the hyperlink.
When mimics, of the type discussed above, are initially generated or regenerated, the mimic accurately reflects the status of the device to which it corresponds. However as a result of the limited number of updates, the displayed mimic can lose synchronization with the device over time due to changes in device status. This is because changes that occur between the generation or regeneration of HTML documents used to implement the mimics will not be reflected in the displayed mimic until the refresh occurs.
Unfortunately, users of such management systems often are not certain when the mimic needs to be updated, e.g., due to the monitored device changing status. In addition, the amount of time required to refresh the screen can be frustrating to users. Thus, the time required to refresh a device mimic may act as a deterrent to a user refreshing the mimic. As a result users may rely upon mimics that inaccurately display network device-status information.
In view of the above, it is apparent that there is a need for new and improved methods and apparatus for implementing device mimics. It is desirable that at least some of the new methods be capable of updating device-status information included in a mimic without having to generate all of the HTML documents representing the entire mimic. It is also desirable that device-status updates occur without the need for a user to request that the displayed mimic be updated or refreshed. It is also desirable that device-status information be updated when a change in device status is detected or at least on a periodic basis so that the device-status information in a mimic be reasonably current.
The present invention relates to methods and apparatus for efficiently displaying and updating information, e.g., device-status information, at a location which is remote from the source of the information.
Specifically, the invention includes methods and apparatus for efficiently generating and updating screens representing device-status information. A management system that includes a Web browser is used to display device-status information transmitted to the management station in the form of an HTML file. The initial HTML file includes a complete description of the status screen to be displayed. Rather than generate and transmit a complete description of the status screen to the management station each time device status changes, a set of device state information in the form of an HTML file is transmitted, e.g., from a remotely located device monitor to the management system.
A program, e.g., a JavaScript routine, is used to update the displayed status information based on the received device state information. Use of a JavaScript routine allows portions of the displayed screen to be modified without having to alter or regenerate the fixed portions of the displayed status screen or the portions relating to device-status information which have not changed. Because device state information is transmitted to update the displayed status information, as opposed to an HTML description of the entire device-status screen, the updating of device-status information is relatively efficient and can be done periodically or whenever a change in device status is detected.
In accordance with the present invention, an image indicating status of a logical or physical device is displayed, e.g., on a computer screen. The displayed status information may be part of a device mimic which graphically represents a device and its status.
Additional features of the present invention are discussed in the detailed description which follows.